Auxiliary power supply for vehicle

ABSTRACT

A vehicle auxiliary electric-power-supplying system can normally stop an electric power inverter by the frequency in use for an electric power supplier being suppressed as low as possible, and electric power being immediately started to be supplied from the power supplier to a controller in a case in which normal electric power has become unable to be obtained from power-outputting of the electric power inverter. The system includes: the electric power inverter for converting a first type of dc power received through an overhead wire to a second type of dc power, and supplying the second type of dc power to a dc load; the power supplier for converting the first type of dc power received through the overhead wire to a third type of dc power; a power-outputting unit, connected to both the electric power inverter and the electric power supplier, for outputting either the second type of dc power or the third type of dc power; and the controller for receiving power from the power-outputting unit, and controlling the electric power inverter.

TECHNICAL FIELD

The present invention relates to vehicle auxiliaryelectric-power-supplying systems that supply low-voltage power, which isconverted from high-voltage power, to loads such as an air conditionerand lighting fixtures installed in an electric vehicle.

BACKGROUND ART

Generally, an electric vehicle has a back-up battery therein. Moreover,a vehicle is provided therein with a vehicle auxiliaryelectric-power-supplying system that converts high-voltage powersupplied from an overhead wire, to low-voltage power, and supplies thelow-voltage power to a load installed in the vehicle. Only when electricpower has been supplied from the back-up battery voltage to a controllerof the vehicle auxiliary electric-power-supplying system, and thecontroller has operated, the entire vehicle auxiliaryelectric-power-supplying system has become ready to start. However, whenvoltage of the back-up battery decreases and does not reach enoughvoltage to operate the controller, the controller does not start tooperate, resultantly the entirevehicle-auxiliary-electric-power-supplying- system does not operate.

Therefore, as disclosed, for example, in FIG. 1 and FIG. 2 of JapaneseLaid-Open Patent Publication 259,704/1989, an electric power supplier(converter) has been provided for converting the high-voltage power,which is supplied from the overhead wire, to the low-voltage power, andsupplying the electric power (electric power source) to the controller(control circuit), when the vehicle auxiliary electric-power-supplyingsystem starts to operate. In response to the operation of the powersupplier, when the vehicle starts to operate, even though the voltage ofthe back-up battery has decreased, the controller in the vehicleauxiliary electric-power-supplying system normally operates withelectric power being supplied from the power supplier.

However, in the above described vehicle auxiliaryelectric-power-supplying system, there has been the following problem.The power supplier, in order to reduce its frequency in use, operatesonly when the vehicle auxiliary electric-power-supplying system startsto operate, then the operation is stopped after electric power has beenobtained from output of an electric power inverter. If any short-circuitmalfunction occurs during the starter stop, due to an affect such as adielectric breakdown on the low-voltage side between the electric powerinverter and the load, in order to stop the output from the electricpower inverter, the controller needs to command the electric powerinverter to stop operation. However, because normal electric power fromthe electric power inverter cannot be obtained due to short-circuit, andin addition, the power supplier is also stopped, the power for thecontroller is stopped; consequently, a normally stopping operation ofthe electric power inverter based on the command from the controller hasbeen impossible.

An objective of the present invention, which has been made to solve theforegoing problem, is to obtain a vehicle auxiliaryelectric-power-supplying system that can suppress the frequency in usefor a power supplier as low as possible, and can normally stop anelectric power inverter by the power supplier being immediately startedto supply electric power to a controller, even in a case in which normalelectric power has become unable to be obtained from the output of theelectric power inverter.

DISCLOSURE OF THE INVENTION

A vehicle auxiliary electric-power-supplying system according to thepresent invention includes: an electric power inverter for converting afirst type of dc power received through an overhead wire to a secondtype of dc power, and supplying the second type of dc power to a dcload; an electric power supplier for converting the first type of dcpower received through the overhead wire to a third type of dc power; apower-outputting unit, connected to both the electric power inverter andthe electric power supplier, for outputting either the second type of dcpower or the third type of dc power; and a controller for receivingpower from the power-outputting unit, and controlling the electric powerinverter; therefore, the system can suppress the frequency in use forthe power supplier as low as possible, and can normally stop-theelectric power inverter by the power supplier being immediately startedto supply electric power to a controller, even in a case in which normalelectric power has become unable to be obtained from the output of theelectric power inverter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a configuration of avehicle-auxiliary-electric-power-supplying system according toEmbodiment 1 of the present invention;

FIG. 2 is a view illustrating a configuration of a vehicle auxiliaryelectric-power-supplying system according to Embodiment 2 of the presentinvention; and

FIG. 3 is a view illustrating a configuration of a vehicle auxiliaryelectric-power-supplying system according to Embodiment 3 of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention will be described in further detail with reference to theaccompanying drawings.

EMBODIMENT 1

FIG. 1 is a view illustrating a configuration of a vehicle auxiliaryelectric-power-supplying system according to Embodiment 1 of the presentinvention. In this figure, numeral 1 denotes an overhead wire, andnumeral 2 denotes a pantograph; here, high-voltage power from theoverhead wire 1 is supplied to the vehicle auxiliaryelectric-power-supplying system through the pantograph 2. As theoverhead wire 1, a wire placed above ground or in a third rail of subwaysystems is quoted as the example.

The configuration in the vehicle auxiliary electric-power-supplyingsystem is explained. Numeral 3 denotes an automatic starter, which iscomposed of a fuse 4, an electromagnetic contactor 5, and an inputfilter reactor 6. In the electromagnetic contactor 5, a coil, a switch,and a resistor for decreasing voltage are represented. In addition, acontactor, which is not illustrated, is provided between the resistorand the coil. A controller described later detects any excessive voltageinputted through the pantograph 2, and opens the contactor; as a result,current will not flow through the coil, enabling the switch to open.Because the contactor is normally closed, the starter automaticallystarts to operate; the coil is excited; the switch is closed; and then,the high-voltage power is applied to the vehicle auxiliaryelectric-power-supplying system. In response to excessive currentthrough the overhead wire 1, by the fuse 4 breaking up, the connectionbetween the overhead wire 1 and the circuits in the vehicle auxiliaryelectric-power-supplying system is disconnected.

Numeral 7 denotes an electric power inverter, which is composed of acharging switch 8, an input filter capacitor 9, an inverter 10, atransformer 11, a rectifier 12, and a smoothing filter 13. The electricpower inverter 7 converts to low-voltage dc power high-voltage dc powerinputted from the automatic starter 3, and supplies the low-voltagepower to a load and the vehicle auxiliary electric-power-supplyingsystem. A smoothing operation for the voltage obtained through theoverhead wire 1 is performed using the input filter reactor 6 and theinput filter capacitor 9. The charging switch 8 controls, for thepurpose of protecting the input filter capacitor 9 when the vehiclestarts to operate, the electric charging based on the controllerdescribed later. The inverter 10 is used for converting dc electricpower into ac. The transformer 11 transforms to low-voltage power thehigh-voltage ac power obtained through the inverter 10. The rectifier 12rectifies into dc power the low-voltage ac power obtained through thetransformer 11. The smoothing filter 13 smoothes the low-voltage dcpower obtained through the rectifier 12 so as to enable the power to besupplied to a load in the following stage.

Numeral 14 denotes a controller, which normally controls the electricpower inverter 7. The controller 14, in order to protect the inputfilter capacitor 9, detects the electric charging state thereof (notillustrated in the figure), and outputs control signals to the chargingswitch 8. After the charging has been performed, the controllerindicates to the inverter 10 a converting operation.

Numeral 15 is an electric power supplier, which is composed of aninverter 16, a transformer 17, and a rectifier 18. The power supplier 15converts to low-voltage dc power the high-voltage dc power obtainedthrough the automatic starter 3. The voltage outputted from the powersupplier 15 is lower than the voltage outputted from the electric powerinverter 7. Both the voltages are controlled by the coil configurationsof the transformer 11 and transformer 17.

Numeral 19 is a butt-jointed diode, in which each cathode of a diode 20and a diode 21 is butt-jointed, and connected to the controller 14.Anodes of the butt-jointed diode 19 each are connected to the smoothingfilter 13 and rectifier 18, respectively. Due to the butt-jointed diode19, higher voltage power of either the power supplied from the electricpower inverter 7 or power supplier 15 is supplied to the controller 14.Although voltages of the above described electric power supplied to thebutt-jointed diode 19 are different from each other, the electric powerinverter 7 and the power supplier 15 are configured so that both thevoltages fall within an electric power supplying range in which thecontroller 14 can normally operate.

Numeral 22 denotes a dc load such as lighting fixtures, to which thelow-voltage dc power is supplied from the smoothing filter 13.

Next, an operation of the vehicle auxiliary electric-power-supplyingsystem is explained.

The vehicle auxiliary electric-power-supplying system is a unit thatstarts to operate at first in the vehicle, and to the system, thehigh-voltage dc power is supplied from the overhead wire 1 through thepantograph 2. Because the electric power received through the overheadwire l has high-voltage such as 1,500 V, and the power therefore cannotbe used intact in the dc load 22 of the vehicle, the power must beconverted to lower voltage power of such as 100 V, and supplied to thedc load 22. The vehicle auxiliary electric-power-supplying systemperforms this converting.

When the vehicle system starts to operate, the high-voltage powerthrough the pantograph 2 is supplied to the automatic starter 3. Theautomatic starter 3 is an input protector for protecting the powerinverter 7 or power supplier 15 in the following stage against excessivehigh-voltage power. The high-voltage power having passed through theautomatic starter 3 is supplied to the charging switch 8 in the electricpower inverter 7 and the inverter 16 in the power supplier 15. At thispoint of time when the power is supplied to both of the units, becausein the electric power inverter 7 any control signal has not yetoutputted from the controller 14 to the charging switch 8, the chargingswitch 8 has not operated. In contrast, the power supplier 15 operatesbased on the high-voltage power supplied. The high-voltage power isconverted from dc into ac by the inverter 16, and transformed tolow-voltage by the transformer 17. The transformed low-voltage ac poweris rectified into low-voltage dc power by the rectifier 18. Therectified low-voltage power is supplied to the diode 21 of thebutt-jointed diode 19. To the diode 20 connected to the electric powerinverter 7, the electric power is not supplied from the electric powerinverter 7, and the voltage of the power supplied to the diode 21 of thebutt-jointed diode 19 becomes higher than the other; therefore, theelectric power is supplied to the controller 14 as the electric powersource.

With electric power being supplied from this source, the controller 14operates. The controller 14 detects a charging state (voltage, etc.) ofthe input filter capacitor 9, and, based on control information (notillustrated) that has been preinstalled in the controller 14, outputs tothe charging switch 8 control signals in response to the detectionresult. The charging switch 8 controls current, when the system startsto operate, from the input filter reactor 6 to the input filtercapacitor 9 based on the control signals, and protects the input filtercapacitor 9 from being rapidly charged. The input filter capacitor 9 ischarged up to the same voltage as that of the overhead wire 1.

After the input filter capacitor 9 has been charged up, the controller14 outputs control signals to the inverter 10. The high-voltage dc powersupplied to the inverter 10 is converted into ac based on the controlsignals. After having been converted into ac, the electric power istransformed to low-voltage by the transformer 11, and rectified intothee low-voltage dc power by the rectifier 12. Then, the low-voltage dcpower is smoothed by the smoothing filter, and supplied to the dc load22 and to the diode 20 of the butt-jointed diode 19.

In the butt-jointed diode 19, because the voltage supplied to the diode20 becomes higher than that of the diode 21, the power from the diode 20is prioritized, and supplied to the controller 14 as an electric powersource.

In a case in which power from the electric power inverter 7 cannot beobtained due to a short-circuit malfunction that has occurred in thelow-voltage side from the electric power inverter 7 to the dc load 22,because the electric power voltage having been supplied to the diode 20becomes lower than the electric power voltage being supplied to thediode 21, the electric power from the diode 21, as the electric powersource, is immediately supplied to the controller 14. The controller 14outputs control signals to the charging switch 8 and inverter 10, etc.of the electric power inverter 7, and stops the operation of theelectric power inverter 7.

During the electric power being supplied from the diode 20 to thecontroller 14, although the electric power from the diode 21 cannot besupplied due to its low-voltage, the power supplier 15 does not stopoperation and remains in a standby status so as to enable electric powerto be supplied at any time. If the high/low voltage relationship betweenthe diode 20 and diode 21 is inverted, the electric power is suppliedfrom the rectifier 18 to the controller 14 through the diode 21.

The butt-jointed diode 19 has three roles. The first role is to preventthe electric power from being supplied from the power supplier 15 to thedc load 22. The second is, in order to reduce the frequency in use forcircuit elements composing the power supplier 15, to automaticallyswitch the electric power source, which supplies power to the controller14, from the power supplier 15 to the electric power inverter 7, afterthe electric power inverter 7 has started to operate and the powertherefrom has been obtained. The last is to automatically switch theelectric power source, which supplies power to the controller 14, fromoutput, of the electric power inverter 7 to that of the power supplier15, because the output voltage of the power supplier 15 becomes higherthan that of the electric power inverter 7, if power from the electricpower inverter 7 cannot be obtained due to a malfunction, etc.

Here, in order to ensure safety during vehicle maintenance, thepantograph 2 and the fuse 4 may be configured so as to be separable.Moreover, in a case in which the dc load 22 is a backup battery, inorder to prevent battery consumption, a contactor may be provided so asto enable the smoothing filter 13 and the backup battery to be suitablyseparated.

As described above, in the vehicle auxiliary electric-power-supplyingsystem according to Embodiment 1 of the present invention, because powerfrom the power supplier 15 on standby is immediately supplied to thecontroller 14 through the butt-jointed diode 19, when any short-circuitmalfunction occurs in the low-voltage side from the electric powerinverter 7 to the dc load 22, not only the operation of the controller14 can be maintained without breaking up the power supplier of thecontroller 14, but also the normal stop operational can be performedfrom the controller 14 to the electric power inverter 7.

Moreover, the system is configured in such a way that the automaticstarter 3 that automatically starts normally without control by thecontroller 14, and the electric power inverter 7that needs control bythe controller 14 are separated; therefore, after the operation till theautomatic starter 3 has been performed, and when the operation of thecontroller 14 is needed, the power supplier 15 finally starts tooperate. Consequently, the operation of the power supplier 15 during thetime when the controller 14 does not need to operate, can be prevented.

In a configuration such as that the electric power is selectivelysupplied to the controller of the vehicle auxiliaryelectric-power-supplying system by voltages outputted from the backupbattery and the power supplier being butted at each other, if thevoltage of the backup battery has not reach a suppliable voltage to thecontroller, even if the entire vehicle auxiliaryelectric-power-supplying system is in operation, the power supplier hascontinued to supply electric power to the controller until the voltageof the backup battery is charged up to the suppliable voltage. On thecontrary, in cases in which the voltages outputted from the electricpower inverter 7 and the power supplier 15 are butted at each other asrepresented in Embodiment 1, because the voltage of the backup batterybecomes unnecessary in the vehicle auxiliary electric-power-supplyingsystem, a time for the power supplier 15 in use, when the system startsto operate, becomes as short as the time until the power output of theelectric power inverter 7 is obtained. Therefore, the frequency for thepower supplier 15 in use for supplying electric power to the controller14 can be significantly reduced; resultantly, the lifetimes of circuitelements in the power supplier 15 can be extended.

EMBODIMENT 2

Although the vehicle auxiliary electric-power-supplying system in whichonly the dc electric power is outputted has been explained in Embodiment1, a vehicle auxiliary electric-power-supplying system in which both acelectric power and dc electric power are outputted is explained inEmbodiment 2.

FIG. 2 is a view illustrating a configuration of the vehicle auxiliaryelectric-power-supplying system according to Embodiment 2.

In this figure, numeral 23 denotes an electric power inverter, numeral24 denotes an inverter, numeral 25 denotes a smoothing filter, numerals26 and 27 denote transformers, and numeral 28 denotes an ac load. The acload 28 includes an air conditioner. Other numerals are the sameelements as those represented in Embodiment 1.

Similarly to the case in Embodiment 1, when high-voltage dc power issupplied to the inverter 24, the power is converted into high-voltage acpower in the inverter 24. Although the inverter 24 is used forconverting dc into ac, single-phase electric power-outputting system asin Embodiment 1 is not used but three-phase one is employed inEmbodiment 2. In order to prevent noise generation due to thetransformer 26, the high-voltage ac power is smoothed by the smoothingfilter 25. The smoothed power is transformed to low-voltage ac power bythe transformer 26, and then supplied to the ac load 28.

The low-voltage ac power (single-phase electric power-output) from thetransformer 26 is supplied to the transformer 27. The supplied electricpower is further transformed to low-voltage power by the transformer 27,and then rectified by the rectifier 12 from ac into dc. The low-voltagedc power having been smoothed by the smoothing filter 13 is supplied tothe dc load 22 and the diode 20 of the butt-jointed diode 19. In thisembodiment, although the transformer 27 and the rectifier 12 are used,the ac three-phase power outputted from the transformer 26 may insteadbe rectified intact using a three-phase bridge-rectifying-circuit.

After the power-output has been obtained from the electric powerinverter 23, similarly to the case in Embodiment 1, power-output fromthe diode 20 of the butt-jointed diode 19 is supplied as an electricpower source to the controller 14.

As described above, in the vehicle auxiliary electric-power-supplyingsystem according to Embodiment 2, an effect similar to that in thevehicle auxiliary electric-power-supplying system according toEmbodiment 1 can be obtained.

Moreover, the vehicle auxiliary electric-power-supplying system can beobtained, in which electric power can be supplied to both the ac loadand the dc load.

EMBODIMENT 3

FIG. 3 is a view illustrating a vehicle auxiliaryelectric-power-supplying system according to Embodiment 3 of the presentinvention. In this figure, numeral 29 denotes an automatic starterhaving a fuse 30. Numeral 31 denotes an electric power inverter, numeral32 denotes an electromagnetic contactor, numeral 33 denotes an inputfilter reactor, and numeral 35 denotes a controller. Other numerals arethe same as those represented in Embodiment 1.

In the vehicle auxiliary electric-power-supplying system according toEmbodiments 1 and 2, the electromagnetic contactor 5 has beenautomatically started to operate using a resistor that can decrease thevoltage until the system can start to operate; however, in some areas,because the voltage of the overhead wire 1 is so high that there may becases in which an electromagnetic contactor having voltage-resistant.characteristics for enabling automatic start is not available, or thevehicle auxiliary electric-power-supplying system becomes upsized due tothe upsized resistor needed for decreasing the voltage to a voltage withwhich the electromagnetic contactor can automatically start to operate.

In the configuration represented in FIG. 3, the automatic starter 29 inwhich any command from the controller 35 is not needed, when the systemstarts to operate, is composed of only the fuse 30. In the electricpower inverter 31 in which a command from the controller 35 is needed,the electromagnetic contactor 32 and the input filter reactor 33 areinstalled. The fuse 30 prevents excessive current from flowing from theoverhead wire 1 to the electric power inverter 31. The controller 35detects the voltage, etc. from the automatic starter 29 (notillustrated), and controls coils of the electromagnetic contactor 32. Aswitch therein is opened/closed by the action of the coils. Theelectromagnetic contactor 32 is configured in such a way that theresistor for decreasing the voltage, in order to automatically start tooperate, has been removed, and the controller 35 controls the contactoraccordingly.

When the system starts to operate, the controller 35 detects the voltageof the electric power from the automatic starter 29, owing to thepower-outputting from the diode 21 (not illustrated). In a case in whichthe voltage is higher than the voltage that the electric power inverter31 can permit, by the controller 35 controlling the coils of theelectromagnetic contactor 32, the switch is opened; consequently, theelectric power inverter 31 is protected against excessive voltagethrough the overhead wire 1. On the other hand, in a case in which thevoltage is within the permissible range, by the controller 35controlling the coils of the electromagnetic contactor 32, the coils areexcited and the switch is closed, and then the input filter reactor 33,the charging switch 8, and the input filter capacitor 9 are turnedactive. The fuse 30 and the electromagnetic contactor 32 each are aprotector for protecting, against the electric power through theoverhead wire 1, the power inputting into the electric power inverter31. The electromagnetic contactor 32 is operated by the controller 35controlling.

After the input filter capacitor 9 has been charged, by the controller35 controlling, the inverter 10 is operated; consequently, thehigh-voltage dc power is converted into ac. Moreover, by the transformer11, the rectifier 12, and the smoothing filter 13, the ac power ischanged into low-voltage dc power. If any power-output is obtained fromthe electric power inverter 31, power-output from the diode 20 of thebutt-jointed diode 19 is supplied to the controller 35 as an electricpower source.

Because the vehicle auxiliary electric-power-supplying system accordingto Embodiment 3 is configured as described above, an effect similar tothat in Embodiment 1 can be obtained.

Moreover, even in a case in which the voltage on the overhead wire 1 isexcessively high, the vehicle auxiliary electric-power-supplying systemwill not be upsized.

As described above, according to the present invention, the vehicleauxiliary electric-power-supplying system can be obtained, in which thefrequency in use for the power supplier is prevented as low as possible,and the electric power inverter operation can be normally stopped byelectric power being immediately started to be supplied from the powersupplier to the controller even in a case in which normal electric powerhas become unable to be obtained from the output of the electric powerinverter.

The present invention is useful in electric vehicles to realize avehicle auxiliary electric-power-supplying system, in which thefrequency in use for the power supplier is prevented as low as possible,and the electric power inverter operation can be normally stopped byelectric power being immediately started to be supplied from the powersupplier to the controller even in a case in which normal electric powerhas become unable to be obtained from the output of the electric powerinverter.

1-8. (canceled)
 9. A vehicle auxiliary electric-power-supplying systemcomprising: an electric power inverter for converting a first type of dcpower received through an overhead wire to a second type of dc power,and supplying the second type of dc power to a dc load; an electricpower supplier for converting the first type of dc power receivedthrough the overhead wire to a third type of dc power; apower-outputting unit, connected to both the electric power inverter andthe electric power supplier, for outputting either the second type of dcpower or the third type of dc power; and a controller for receivingpower from the power-outputting unit, and controlling the electric powerinverter.
 10. A vehicle auxiliary electric-power-supplying system asrecited in claim 9, wherein the electric power inverter converts thefirst type of dc power into a fourth type of ac power, and supplies thefourth type of ac power to an ac load.
 11. A vehicle auxiliaryelectric-power-supplying system as recited in claim 9, wherein to thecontroller the third type of dc power is supplied through thepower-outputting unit when the system starts to operate, and the secondtype of dc power is supplied through the power-outputting unit after thesecond type of dc power has been outputted from the electric powerinverter.
 12. A vehicle auxiliary electric-power-supplying system asrecited in claim 11, wherein the electric power inverter converts thefirst type of dc power into a fourth type of ac power, and supplies thefourth type of ac power to an ac load.
 13. A vehicle auxiliaryelectric-power-supplying system as recited in claim 11, wherein thethird type of dc power is supplied to the controller through thepower-outputting unit if the voltage of the second type of dc powerbeing supplied becomes lower than the voltage of the third type of dcpower being supplied.
 14. A vehicle auxiliary electric-power-supplyingsystem as recited in claim 13, wherein the electric power inverterconverts the first type of dc power into a fourth type of ac power, andsupplies the fourth type of ac power to an ac load.
 15. A vehicleauxiliary electric-power-supplying system as recited in claim 13,wherein the power-outputting unit is constituted of a butt-jointed diodecomposed of a first diode to which the second type of dc power issupplied and a second diode to which the third type of dc power issupplied, so as to supply output of either power to the controller. 16.A vehicle auxiliary electric-power-supplying system as recited in claim15, wherein the electric power inverter converts the first type of dcpower into a fourth type of ac power, and supplies the fourth type of acpower to an ac load.
 17. A vehicle auxiliary electric-power-supplyingsystem as recited in claim 15, further comprising: a first protector,connected between the overhead wire and the electric power inverter, forprotecting the electric power inverter against the first type of dcpower supplied through the overhead wire.
 18. A vehicle auxiliaryelectric-power-supplying system as recited in claim 17, wherein theelectric power inverter converts the first type of dc power into afourth type of ac power, and supplies the fourth type of ac power to anac load.
 19. A vehicle auxiliary electric-power-supplying system asrecited in claim 17, wherein the first type of dc power is supplied tothe electric power supplier through the first protector.
 20. A vehicleauxiliary electric-power-supplying system as recited in claim 19,wherein the electric power inverter converts the first type of dc powerinto a fourth type of ac power, and supplies the fourth type of ac powerto an ac load.
 21. A vehicle auxiliary electric-power-supplying systemas recited in claim 19, wherein the electric power inverter comprises asecond protector for protecting, according to control from thecontroller, the inverter internally against the first type of dc power.22. A vehicle auxiliary electric-power-supplying system as recited inclaim 21, wherein the electric power inverter converts the first type ofdc power into a fourth type of ac power, and supplies the fourth type ofac power to an ac load.